Control switch unit



March 22, 1938; B. E. SHAW CONTROL SWITCH UNIT 2 sheetssheet 1 Filed May 25, 1936 Il UM Mmh 22, 1938. B E, SHAW 2,111,816

CONTROL SWITCH UNIT Filed May 25, 1956 2 Sheets-Sheet 2 Patented Mar. 22, 1938 UNITED STATES 2,111,816 y CONTROL SWITCH UNIT Burton E. Shaw, Adel,

iowa, assignor to Penn Electric Switch Co., lDes Moines, Iowa, a corporation of Iowa f Application May 25,

19 Claims.

An object of my invention is to provide a control switch in the form of a unit which can be associated with any type of controlling element,

the unit being comparatively simple and inexpen- ,5 lsive from a manufacturing standpoint.

A further object is to provide a control switch unit which is capable oi carrying considerable current, yet can be made of very small size so as to take up but little room in a casing or on a panel' closed in the housing, terminal connections being I 15 provided on one face of the housing and the opposite vtace thereof being adapted `for mounting on a, panel or the like, such other face having projecting from it an actuating element with which a control element can be operatively con- 10 nected.

A further object is to provide a switch constrainedto one position and means projecting from the housing for the switch which, when pushed inwardly, will move the switch to the other position and when released, will permit it to move to said one position. e

A further object is to provide switch mechanism contained in a housing. including a switch arm and a pair of contacts, the contacts being so mounted and constructed that any rebounding thereof upon closure is entirely eliminated.

Still another object is to provide a switch of the type having a magnet to produce snap action, the switch including a switch arm for operating the switch contacts and the armature being adjustable relative to the arm to vary the differential of operation of theswitch, a stop being provided for the switch arm to always position it in the` same position when closed and in the same relationship tothe contacts regardless of the adjustment for change in differential of operation. A further object is to provide a pair of switch contactsland a leaf spring for mounting one of them, the leaf spring being under' tension to engage the contacts and being separable by operation of a switch arm, which switch arm engages the leaf spring for separating purposes and disengages it for permitting the contacts to close, the leaf spring being comparatively small and light to eliminate any possibility of its momentum causing rebounding of the contacts upon closure of the switch. l

With these and other objects in View my invention consists in the construction, arrangement and combination of the various parts of my device, whereby the objects contemplated are attained', as hereinafter more fully set forth, pointed out in my claims and illustrated in the, accompanying drawings, in which: 1 Figure 1 is .a side elevation of a control switch was, ser-iai No., einer (ci. 20o- 139) unit embodying my invention, showing the device approximately full size and associated with a surface temperature type of controlling element attached to a steam pipe, the switch unit being shown in an inverted position relative to the remaining figures of the drawings.

Figure 2 is an enlarged plan View of the switch unit with the cover omitted.

Figure 3 is a side elevation of the switch unit showing the cover in cross section.

Figure 4 is a sectional View on the line 4-4 of Figure 2.

Figure 5 is. a sectional view on the line 5-5 of Figure 3.

to Figure 3 showing On the accompanying drawingsj have used thereference numeral I@ to indicate a base and I2 a cover associated 'with the base. The cover and base are retained together by means of a pair of screws i4 extending through perforations Igof the base il! and bores I8 of bosses 20 of the cover I2. The base I0 is provided with sockets 2E to receive the lower ends of the bosses ZIJ while the peripheral edge of the cover I2 rests on a shoulder 24 of the base.

Screws i4 also serve the purpose of mounting the entire switch unit on a panel or the like, it being shown as mounted on the wall 26 of a casing (illustrated in Figure 1) which is attached to a steam pipe or the like 28 by means of bands 30 Within the casing 26 a bimetal controlling ele- Figure 6 is a sectional view on the line 5-6 of' ment 32 is illustrated which is of folded character and'pivoted at 33, 'one end thereof beingadjustably anchored while the other end is adapted to engage an operating element 34 extending from the cover I2.

The operating element 34 is a pin made preferably of. insulation and extending slidably through a boss 36 of the cover I2. Within the housing formed by the base III and the cover I2, I provide a pivot bracket 38, which is L shaped in side elevation, as shown in Figure 3, and is secured to the base I0 by screws 4l)` or the like.

Riveted tothe bracket 38 is a pivot blade 42 made of thin sheet metal, the upper end of which is adapted to coact with a V seat 44 formed in a switch arm 46. The switch arm is preferably forked as shown in Figure 2 so that there are two of the seats 44 and these seats are retained against the upper edges of the blade 42 by a spring 48. The upper end of the spring 48 bears against across bar 50 (see Figure 5) of the bracket 38 while the lower end thereofbears against an extension 49 of the switch arm .46.

CII

The spring 48 is substantially in alignment with the pivotal axis of the switch arm.

For actuating the switch arm 46 from. the operating pin 34 a spring 31 is interposed between the two, the purpose of which will hereinafter appear. A stop bracket 5I is provided for the right hand end of the switch arm 46 and this bracket is secured in position by screws 52 and 54. One end of a leaf spring 56 is secured on the base l by being interposed between the stop bracket and the base. An armature 58 is provided for the switch arm 46 and this is in the form of a disc having a screw threaded extension 60 threaded through the switch arm 46.

A permanent magnet 6l is provided for attracting the armature 58. This magnet is in the usual U shape and may be retained in a socket 63 of the base I0 by a screw or the like as shown in Figure 6 at 65, It will be noted that the leaf spring 56 extends through the magnet 6| between the poles thereof (see Figure 6),

A leaf spring 62 is provided for retaining the armature 58 in any position to which it may be adjusted.

A movable contact 64 is carried by the leaf spring 56 and is normally engaged with a stationary contact 66 mounted on the base I0. Terminals are provided for the switch, one of which is the screw 54 and the other of which. is illustrated at 68. y

The heads of these screws are located on the bottom of the base I0 where they are accessible for making electrical connections with the switch without having to extend to a position within the switch unit. 'I'he leaf spring 56 is provided with a cam shaped terminal end adapted to be engaged by an extension 12 of the switch arm 46 when the switch arm is moved to open circuit position as shown in Figure 4.

In Figure '7 I have shown a modified construction in which the leaf spring 56a does not extend through the magnet 6|a and accordingly I eliminate the electromagnetic effect of the current flowing through the switch on the magnet. This effect is produced in Figure 3 due to the current flowing through the switch in such manner that it is equivalent to a coil of one turn on the magnet, whereas such effect is eliminated with the construction of Figure '7.

A further modification is shown in Figure 8 wherein a leaf spring 12b is biased downwardly and may be adjusted toward the switch arm 46 by a screw 12e threaded in a boss 12d of the spring 12b. By this means the position at which the spring 56h will be picked up in relation to the position of the switch arm 46 as it moves to open position may be predetermined as desired.

` Practical operation In the operation of my switch, the parts are normally in the position of Figure 3 with the contacts 64 and 66 in position for closing the circuit. It will be noted that the extension 12 of the switch arm 46 is slightly spaced from the cam end 10 of the leaf spring 56, as best shown in Figure '7. When the operating element, or pin, 34 is pushed inwardly far enough to compress the spring 31 to place it under suiicient tension to overcome the magnetic attraction of the magnet 6I on the armature 58, the switch arm will be swung to the open circuit position of Figure 4 due to the built up tension in the spring and this will occur with snap action as immediately upon the switch arm 46 leaving the stop 5I the armature 58 will be in a weaker magnetic field, thus permitting it to be greatly overbalanced by the tension in the spring and thereby cause the desired upward swing of the switch arm 46. Soon after the switch arm leaves the stop 50, the extension 12 will engage the cam end 10 of the spring 56 and swing it to the open circuit position of Figure 4. The operating element 34 of course is pushed inwardly by any desired actuating device, such as the bimetal strip 32 (see Figure l) which upon becoming heated, warps to the dotted line position illustrated.`

When the operating pin 34 is permitted to move outwardly the tension of the spring 31 will be lessened and finally the magnetic influence on the armature 56 will be sufficient to swing the switch arm 46 to closed circuit position against the stop 5I which permits the leaf spring 56 to engage the contact 64 with the contact 66.

Since a leaf spring has but little inertia and the contact 64 has but little mass, the contacts when they once engage will remain so without any danger of rebounding, which results in a clean make", which cannot be secured with switches of the type where the contacts are mounted on the armature which has considerable mass and therefore momentum which causes rebounding.

Since the extension 12 is spaced from the cam end 10 in the closed position of the switch, it is evident that there is no connection at this time between the armature and the leaf spring 56 and therefore the armature can rebound slightly without separating the contacts. This isolates the closing action of the switch arm from the closing action of the contacts so that the inertia of only the leaf spring 56 and the contact 64 need be considered, and since, as before stated, these are slight, the problem of arcing at the contacts upon closure is entirely eliminated.

If it is desirable to adjust the switch for a different diierential of operation the armature 56 can be rotated either toward or away from the magnet 6I to secure either wider or narrower differential. This adjustment, due to the arrangement shown, is accomplished without changing the relation of the extension 12 to the cam end 10 of the leaf spring so that the spacing between these two part's is not disturbed by such adjustment.

It is sometimes desirable to change this spacing so that the contacts will be separated a different period of time after the switch arm 46 reaches the stop 5|. 'I'his is accomplished at the factory by bending the extension 12 and may be accomplished in a more facile manner, as shown in Figure 8, by arranging the extension 12b, so that it is readily adjustable relative to the switch arm 46, this being accomplished by the use of the adjusting screw 12o.

From the foregoing description, it will be obvious that I have provided a very small switch unit which is comparatively simple and which can be mounted in connection with any type of actuating device, the switch unit being self-contained, being provided with its own terminals for electrical connections and having merely a contact connection with an actuating element. The switch is therefore readily removable as a unit when anything goes wrong with it so that another switch unit can be substituted in a minimum of time,

Also the switch unit can be adapted for a full line of different types of actuating devices withanime out the necessity of redesigning a switch for any of them. The switch is quite compact, which compactness resides somewhat in the arrangement of the leaf spring 56, in Figure 3, extending through the magnet 6l.

It is desirable to have a reasonably long leaf spring to get the best results therefrom, although this arrangement does have the effect of one turn of the current carrying wire around the magnet.

Where this effect is undesirable, the leaf spring 56a can be shortened as in Figure "1. The shorter leaf spring as shown in Figure 7 will be found y satisfactory in many installations.

The switch is so constructed that the pivot mechanism-is quite simple, yet relatively friction free.

Some changes may be made in the construction and arrangement of the parts of my device without departing from the real spirit and purpose of my invention and it is my intention to cover by my claims any modified forms of structure or use ,of mechanical eduivalentswhich maybe reasonably included within their scope.

I claim as my invention: y

l. In a control switch unit, a housing, a switch arm therein, a magnet. within said housing and biasing said switch arm to one position, means projecting from said housing for actuating said switch arm to its other position and contacts 'thin said housing, independent of said switch arm and normally engaged, said switch arm having means operative to disengage said contacts from each other when said switch arm is moved to said other position, said means being disengaged from said contacts when said switch arm is in said one position,

2. In a control switch unit, a housing, a switch arm therein, an armature carried by said switch arm, a stop for said switch arm, a magnet cooperating with said armature to constrain said switch arm to engage said stop, said armature being adjustable relative to said switch arm and thereby relative to said magnet and the switch arm being maintained in 4a predetermined position relative to said housing by said stop regardless of the position of adjustment of said armature, a pair of contacts within said housing, one contact being stationary and a leaf spring having the other contact mounted thereon, said contacts, when said leaf spring is in one position, being engaged and, when said leaf spring is in another position, being disengaged, said switch arm having means engaging said leaf spring to move it from one of its positions to the other one when Asaid switch arm is moved to one of its positions.

3. In a switch' structure, a base, a magnet mounted thereon, a switch arm having a V seat and pivot connection with said base, means retaining said seat in contact with said pivot connection, a leaf spring' mounted on said base and 'extending through said magnet, a stationary contact on said base, a movable contact mounted on said leaf spring and means on said switch arm to engage said leaf spring to separate said contacts when said switch arm is moved away from said magnet.

4. In a switch structure, a base, a magnet mounted thereon, `a switch arm having a V seat and pivot connection with said base, means retaining said seat in contact with said pivot connection, a leaf spring mounted -on said base and extending through said magnet, a stationary contact on said base, a movable Contact mounted on said leaf spring, means on said switch arm to engage said leaf spring to separate said contacts when said switch arm is moved away from said magnet, and means for so moving said armature comprising an operating element and a spring interposed between said operating element and said arm.

5. In a switch structure, a base, a magnet mounted thereon, alswitch arm having a V seat and pivot connection with said base, means retaining said seat in contact with said pivot connection, a leaf spring mounted on said base and extending through said magnet, a stationary contact on said base, a movable contact mounted on said leaf spring, and means on said switch arm to engage said leaf spring to separate said contacts when said switch arm is moved away from said magnet, said last means being variable relative to said switch arm to vary the engagement of said last means in relation to the distance said armature moves away from said magnet before separating said contacts.

6. In a switch structure, a base, a magnet mounted thereon, a switch arm having a V seat and pivot connection with said base, means retaining said seat in Contact with said pivot connection, aleai spring mounted on said base, a stationary contact on said base, a movable contact mounted on said leaf spring, and means on said switch arm to engage said leaf spring to separate said contacts when said switch arm is moved away from said magnet.

7. In a switch structure, a base, a magnet mounted thereon, a switch' arm having a V seat and pivot connection with said base, means retaining said `seat in contact'with said pivot connection, a leaf spring mounted on said base, a stationary contact on said base, a movabie contact mounted on said leaf spring, means on said switch arm to engage said leaf spring to separate said contacts when said switch arm is moved away from said magnet, a cover for said base, and means for so moving said armature comprising an operating element extending through said cover.

8. In a control switch unit, a switch housing including a base, a pivot bracket thereon, a switch arm pivoted to said pivot bracket, an armature onsaid switch arm, a magnet, a stop for said switch arm to normally position said armature spaced from said magnet, an operating element extending from said switch housing for moving said switch arm in a direction for said armature` to move away *from said magnet and contacts controlled by said switch arm and engaged in said switch housing, said contacts comprising a stationary contact and a leaf spring mounted contact normally engaged with each other, said switch arm having an operative connection with said leaf spring to separate said contacts in one position of the switch arm.

9'. In a control switch unit, a switch housing including a base, a pivot bracket mounted thereon, a switch arm pivoted to said pivot bracket, a stop for said switch arm, means biasing said switch arm to engage said stop, an operating element extending from said switch housing, a stationary contact, a leaf spring, a movable Contact carried thereby and normally engaged, due to the resiliency of said leaf spring, with said stationary contact and a projection on said switch arm to engage said leaf spring and cause the contact. carried thereby to be separated from said stationary contact after said switch arm has been moved from said stop.

10. In a control switch unit, a switch housing including a base, a pivot bracket thereon, a switch arm pivoted to said pivot bracket, an armature on said switch arm, a magnet, a stop for said switch arm to normally position said armature spaced from said magnet, an operating element extending from said switch housing for moving said switch arm in a direction for said armature to move away from said magnet, contacts controlled by said switch arm and enclosed in said switch housing and a spring interposed between said operating element and said switch arm.

1l. In a control switch unit, a switch housing including a base, a pivot bracket thereon, a switch arm pivoted to said pivot bracket, an armature having a screw threaded connection with said switch arm, a magnet, a stop for said switch arm to position said armature relative to said magnet, said armature upon beingrotated while said switch arm is in engagement with said stop, assuming positions at different distances from said magnet.

12. A control switch unit comprising a housing, a pivotal mounting adjacent one end thereof, a switch arm pivoted to said pivotal mounting, a magnet adjacent the other endI thereof, said switch arm having an armature normally positioned adjacent said magnet, a leaf spring anchored at said other end of said housing and extending through said magnet to a position adjacent said pivot bracket, a contact carried thereby, a stationary contact, said leaf spring normally engaging said contact carried thereby with said stationary contact, said switch ann having a portion extending beyond said pivot bracket,

an operating element extending through said housing and engageable with said portion and means on said switch arm for permitting said contacts to close in one position of the arm and moving said leaf spring to disengage them in the other position thereof.

13. In a control switch structure, a switch housing including a base, a pivot plate extending upwardly therefrom, a switch arm having a V seat biased to engage the edge of said pivot plate, an armature on said switch alm, a magnet, a stop for said switch arm to position said armature normally adjacent said magnet, an operating element extending through said switch housing for moving said switch arm in a direc tion away from said magnet and contacts controlled by said leaf spring and enclosed in said switch housing.

14. In a control switch unit, a switch housing including a base, a pivot bracket mounted thereon, a, switch arm pivoted to said pivot bracket, a stop for said switch arm, means biasing said switch arm to engage said. stop, an operating element extending from said switch housing, a stationary contact, a leaf spring, a movable contact carried thereby and normally engaged, due: to the resiliency of said leaf spring, with said stationary contact and a projection on said switch arm. to engage said leaf spring and cause the movable contact to be thereby separated from said stationary contact after said switch arm has been moved from said stop, said leaf spring having a cam shaped surface and said switch arm having a portion movable about the pivotal axis of said switch arm for engaging said cam shaped surface to separate said contacts.

15. In a control switch, a support, a switch arm pivoted thereto, an armature having a screw threaded connection with said switch arm, a magnet, a stop for said switch arm to position said armature relative to said magnet, said armature, upon being rotated, assuming positions at different distances from said magnet and Said switch arm being maintained in a predetermined position relative to said base by engaging said stop.

16. In a control switch, a support in the form of a housing, a switch actuating arm pivoted therein, normally engaged contacts mounted therein and separable from each other by said switch actuating arm, a magnet, an armature cooperable therewith and having a variable connection Wiih said switch actuating arm for changing the diiierential of operation of the control switch, a stop for limiting movement of said switch actuating arm in one direction to a predetermined position relative to said magnet and relative to said contacts, said armature, upon being varied in position relative to said switch actuating arm lwith said switch actuating arm in said predetermined position, assuming positions at different distances from said magnet without changing the relative positions of said switch actuating arm, stop and contacts.

17. In a control switch, a support, a switch actuating arm pivoted relative thereto, a stop for said switch actuating arm in predetermined position relative to said support, a magnet biasing said switch actuating arm to engage said stop, a. pair of relatively movable contacts, a. movable element carrying one of said contacts, said contacts being normally enga-ged, said switch actuating arm being spaced from said movable element when said switch actuating arm is in said predetermined position, an armature having variable connection with said switch actuating arm and thereby variable in spacing relative to said magnet to vary the diierential of operation of said control switch, said switch actuating arm being retained in its position rela.- tive to said movable element without respect to the variable conditions under operation resulting from adjustment of said armature relative to said switch actuating arm for differential varying purposes.

18. In a control switch, a support, a switch arm pivoted relative thereto, a. magnet, an armature having a variable connection with said switch arm to change the differential of operation of the control switch and lying in a plane substantially parallel to a plane joining the poles of said magnet, a stop for said switch arm to position said armature relative to said magnet, contacts operable by said switch arm, said armature upon being varied in position relative to said switch arm assuming positions at different distances from said magnet and the position of said switch arm and said contacts relative to each other being unchanged by variation in position of said armature relative to said switch arm.

19. In a control switch, a support, a pair of contacts mounted on said support and normally spring-pressed to closed position, a movable element for separating said contacts, a switch arm pivoted relative to said support and operative to engage said movable element for separating said contacts, a stop for limiting movement of said switch arm, a magnet, an armature on said switch arm and cooperabie with said switch arm to secure snap action of the control switch, said switch arm being spaced from said movable element when said switch arm is in engagement with said stop.

BURTON E. SHAW. 

